Plano-Convex Lenses have a positive focal length and near-best-form shape for infinite and finite conjugate applications. They can be employed to converge collimated beams or collimate light from a point source. To minimize the introduction of spherical aberration, a collimated light source should be incident on the curved surface of the lens when being focused and a point light source should be incident on the planar surface when being collimated.
The focal length of each lens can be calculated using a simplified thick lens equation:
f= R/(n-1),
where n is the index of refraction and R is the radius of curvature of the lens surface.
They can be also coated with MgF2 to protect the surface or AR coated to increase the transmission.